1. Field of the Invention
The present invention relates to circuit boards, more specifically it relates to mounting components on a circuit board.
2. Description of the Related Art
Typically, the surface of a circuit board contains conductive paths and conductive pads. The conductive pads are used to connect a component to a conductive path which may be on an outer or inner surface of the circuit board. The outer surface of the circuit board is protected by a mask of nonconductive material. This mask usually covers the entire top surface of the circuit board except for the pads. The pads are left uncovered to permit soldering components to the pads.
FIG. 1 illustrates component 10, with conductive contacts 12 and 14, mounted to circuit board 16. Contact 12 is connected to pad 18 by solder 22 and contact 14 is connected to pad 20 by solder 24. Upper surface 26 of circuit board 16 is protected by mask 28. Mask 28 covers all of surface 26 except for the areas including and surrounding pads 18 and 20. Pads 18 and 20 are left uncovered so that electrical contact can be made with the conductive contacts of component 10.
FIG. 2 is a top view of circuit board 16 illustrating the areas not covered by mask 28. Areas 36 and 38 are the portions of upper surface 26 that are not covered by mask 28. Area 36 leaves pad 18 and a small portion of top surface 26 uncovered. Area 38 leaves pad 20 and a small portion of surface 26 uncovered.
Referring to FIG. 1, this component mounting technique results in space 44, which is the space between the top surface of mask 28 and the bottom surface of component 10, being rather small. A typical height for space 44 is approximately 0.002 inches.
During the manufacturing process, it is typical for solder flux and other residue to become trapped in space 44. In the past, this debris was removed by cleaning the assembled circuit board using CFCs. It has been learned that CFCs damage the earth's ozone layer, and therefore it is no longer desirable to use such a substance to remove the debris from space 44.
Water is one of the more desirable substitutes for a CFC cleaning solution. Unfortunately, water does not remove debris from space 44 as thoroughly as CFCs. Therefore, it is desirable to mount components to a circuit board in a fashion that allows thorough cleaning using water.